Electronic central locking system

ABSTRACT

The security to prevent theft of a central locking system for motor vehicles is improved by arranging a switch  34, 340,  which can be switched by a coded signal, in the supply voltage lines  31  and/or  310  and/or  32  for driving an actuating element. (FIGS.  2, 3 ).

[0001] The invention relates to an electronic central locking system formotor vehicles and operating systems for locks or the like whoseactuating elements are connected, such that they can be switched, viasupply voltage lines to a controller.

[0002] In a known central locking system for motor vehicles, operatingpoints which are designed as infrared receivers or else as receivers forother wire-free signals are constructed on the doors, on the trunk lidand in the vicinity of the starter switch as well as on the filler caplock.

[0003] These operating points are all the same in the known centrallocking system. Each operating point comprises a transmitting devicewhich includes a modulator, an amplifier and an IR diode, and areceiving device having a photo diode, an amplifier and a demodulator.Each of these operating points is connected via in each case two supplyvoltage lines to a controller, which essentially comprises amicrocomputer and an interface circuit (DE-A 36 28 706 A1).

[0004] It is disadvantageous that this known central locking system isnot thief-proof since the actuating elements can be changed to the“open” position by applying external voltages to the supply voltagelines.

[0005] In contrast to this, the invention is based on the object ofimproving a central locking system of the described type such that it isthief-proof.

[0006] It has been found that this object can be achieved in a simplemanner by arranging a switch, which can be switched by coded signal, inthe supply voltage lines for driving an actuating element.

[0007] According to claim 2 of the invention, the switch which can beswitched by the coded signal is arranged in the immediate vicinity ofthe drive for an actuating element.

[0008] This means that application of an external voltage to a supplyvoltage line cannot operate the drive for an actuating element, sincethe supply voltage line is interrupted by the switch immediatelyupstream of the drive. The actuating element cannot be influenced untilthe switch in the supply voltage line has been closed by the correctcoded signal.

[0009] The coded signals for the switches can reach said switches viasignal lines which are arranged between the controller and the switches.

[0010] According to claim 4,. the coded signals can alternatively betransmitted to a switch via the supply voltage line for the drive forthe actuating element.

[0011] It is advantageous if, according to claim 5, the drive for anactuating element, the switch and the switching electronics are combinedto form a unit. An economic and simple circuit is provided by using thevoltage supply for the unit both for supplying the switching electronicsand for supplying the drive for the actuating element.

[0012] In a second exemplary embodiment, the drives for the actuatingelements are driven by data signals which pass via dedicated data linesto the switches and to the switching electronics in order to drive thedrives for the actuating elements.

[0013] According to claims 9 and 10, pulse modulation or amplitudemodulation can be used to apply the coded signals to the supplyvoltages.

[0014] In order to improve the security to prevent theft, the voltagesupply lines and/or the signal and data lines are laid in a concealedmanner.

[0015] Exemplary embodiments of the invention are explained in thefollowing text with reference to the drawing, in which:

[0016]FIG. 1 shows, schematically, major elements of a known centrallocking system,

[0017]FIG. 2 shows an outline circuit diagram of a first embodiment ofthe invention,

[0018]FIG. 3 shows an outline circuit diagram of a second exemplaryembodiment of the invention,

[0019]FIG. 4 shows a more detailed illustration of the first exemplaryembodiment,

[0020]FIG. 5 shows a more detailed illustration of the second exemplaryembodiment.

[0021] In a known electronic central locking system 1, a plurality ofidentical operating points 2, 11, 12 and 13 are provided of which, forthe sake of simplicity, only the operating point 2 will be explained inmore detail. This includes a transmitting device 3 and a receivingdevice 4. The transmitting device 3 includes a modulator 5, an amplifier6 as well an IR diode 7. The receiving apparatus 4 includes a photodiode 8, an amplifier 9 as well as a demodulator 10.

[0022] Each of the operating points 2, 11, 12 and 13 is connected vialines 14 and 15 to a controller 16, which includes a microcomputer 12and an interface circuit 18.

[0023] Actuating elements are supplied via supply voltage lines 31 and32, via outputs 19 and 20 as well as power stages 21 and 22. By way ofexample, an actuating element 23 is used for the driver's door, anactuating element 24 for the front-passenger's door, an actuatingelement 25 for one rear door, an actuating element 26 for the other reardoor, an actuating element 27 for a filling cap lock, and an actuatingelement 28 for a trunk.

[0024] A key 29, which includes a code transmitter 30, is provided tooperate the central locking system 1. The transmitter and the receiversfor the central locking system 1 may operate by radio, or else byinfrared signals.

[0025] When the signals emitted by the code transmitter 30 arrive at areceiving device 4, then this, via the interface circuit 18, emits anappropriate signal to the microcomputer 17. The interface circuit 18adds to this signal information about which receiving device 4 receivedthe signals. The program which is stored in the microcomputer 12 usesthis information to determine information items which operate theactuating element 23 to 28. For example, when the wire-free signals arereceived at the operating points 2 and 11, all the doors and the fillercap are unlocked. When the IR signals are received at another operatingpoint, the doors, the filler cap and the trunk lid are unlocked. Whenwire-free signals are received at the last operating point, close to thestarter switch, only the trunk lid is unlocked.

[0026]FIG. 1 shows that the supply voltage lines 31 and 32 are routeddirectly to the actuating elements 23 to 28. It can be seen that, undersome circumstances, the actuating elements can be moved to the “open”position by applying external voltages to the supply voltage lines 31,32.

[0027]FIGS. 2 and 3 show, schematically, how this can be avoidedaccording to the invention.

[0028] In a first exemplary embodiment according to FIG. 2, thecontroller 16 is connected via power supply lines 31 and 32 and via aswitch 34 to the drive 33 for an actuating element. The switch 34 isfurthermore connected, such that it can be switched, via a signal line35 to the controller 16. The drive 33 for an actuating element and theswitch 34 are combined to form a unit 36.

[0029] This circuit arrangement can be used to switch on the drive 33for one of the actuating elements, via the power supply lines 31 and 32,only if the switch 34 has previously been closed by a coded signal viathe signal line 35. This coded signal is emitted from the controller 16.

[0030]FIG. 3 shows a second exemplary embodiment with a controller 160,which is connected via a supply voltage line 310 and a supply voltageline 32 to a switch 340. This switch 340 is located in the circuit forthe drive 33 for an actuating element, and is combined with this drive33 to form a unit 360. The switch 360 is switched via coded signals,which are passed to the switch 340 via the supply voltage line 310.

[0031]FIG. 4 shows the circuit arrangement according to FIG. 2, indetail. On a unit 38, the drive 33 for an actuating element is directlyconnected to control electronics comprising a power stage 39 and aswitching IC 37. The switching electronics are connected via supplyvoltage lines 31 and 32 to the controller 16. The supply voltage lines31 and 32 also supply voltage to the drive 33.

[0032] The drive 33 is driven via an appropriate data signal(unidirectional or bi-directional data interchange) via the signal line35.

[0033] According to FIG. 5, a drive 33 for an actuating element, a powerstage 39 and a switching IC 370 are combined to form a unit 380. Theswitching IC 370 is connected to the controller 16 via a voltage supplyline 32 and via a further voltage supply lines 310. Coded signals arepassed via the voltage supply line 310 to the switching IC 370, andcause the drive 33 to be switched.

[0034] The signals are applied to the supply voltage lines by, forexample, amplitude modulation or pulse modulation.

[0035] The units 36, 360 and 38, 380 are used, according to theinvention, instead of the actuating elements 23 to 28 in an electroniccentral locking system 1 as shown in FIG. 1. In consequence, it is nolonger possible to operate these actuating elements simply by connectingthe supply voltage lines to external voltages.

[0036] List of designations used

[0037] 1 Electronic central locking system

[0038] 2 Operating point

[0039] 3 Transmitting device

[0040] 4 Receiving device

[0041] 5 Modulator

[0042] 6 Amplifier

[0043] 7 IR Diode

[0044] 8 Photo diode

[0045] 9 Amplifier

[0046] 10 Demodulator

[0047] 11 Operating point

[0048] 12 Operating point

[0049] 13 Operating point

[0050] 14 Line

[0051] 15 Line

[0052] 16 Controller

[0053] 160 Controller

[0054] 17 Microcomputer

[0055] 18 Interface circuit

[0056] 19 Output

[0057] 20 Output

[0058] 21 Power stage

[0059] 22 Power stage

[0060] 23 Actuating element, driver's door

[0061] 24 Actuating element, front-passenger's door

[0062] 25 Actuating element, rear door

[0063] 26 Actuating element, rear door

[0064] 27 Actuating element, filler cap lock

[0065] 28 Actuating element, trunk

[0066] 29 Key

[0067] 30 Coded transmitter

[0068] 31 Supply voltage line

[0069] 310 Supply voltage line with signal transmission

[0070] 32 Supply voltage line

[0071] 33 Drive for an actuating element

[0072] 34 Switch

[0073] 340 Switch

[0074] 35 Signal line

[0075] 36 Unit

[0076] 360 Unit

[0077] 37 Switching IC

[0078] 370 Switching IC

[0079] 38 Unit

[0080] 380 Unit

[0081] 39 Power stage

1. An electronic central locking system (1) for motor vehicles andoperating systems for locks or the like whose actuating elements (23 to28) are connected, such that they can be switched, via supply voltagelines (31, 32) to a controller (16), wherein in order to drive (33) anactuating element (23-28), the supply voltage lines (31, 310, 32)include a switch (34, 340, 37, 370) which can be switched by a codedsignal.
 2. The central locking system as claimed in claim 1, wherein theswitch (34, 340, 37, 370) which can be switched by the coded signal isarranged in the immediate vicinity of the drive (33) for an actuatingelement (23-28).
 3. The central locking system as claimed in claims 1and 2, distinguished by signal lines (35) which are connected to thecontroller (16, 160), via which the coded signals are supplied to theswitches (34, 37).
 4. The central locking system as claimed in claims 1and 2, wherein a supply voltage line (310) for the drive (33) for anactuating element (23-28) is used to transmit the coded signals to aswitch (340, 370).
 5. The central locking system as claimed in claims 1and 3, wherein the d rive (33) for an actuating element (23-28), theswitch (34) and the switching electronics (340, 37, 370, 39) arecombined to form a unit (36, 360, 38, 380).
 6. The central lockingsystem as claimed in claim 5, wherein the supply voltage for the unit(36, 360, 38, 380) is used both for supplying the switching electronics(340, 37, 370, 39) and for supplying the drive (33) for the actuatingelement (23-28).
 7. The central locking system as claimed in one or moreof the preceding claims, wherein the drive (33) for an actuating element(23-28) is driven by data signals, which are connected via data lines(35) to the switches (34) and/or to the switching electronics (340, 37,370, 39).
 8. The central locking system as claimed in claims 1 to 4,wherein the drive (33) is driven by signals which are coded for aswitching element (23-28) and are supplied to the switches (34) and/orthe switching electronics (340, 37, 370, 39) via supply voltage lines(31, 310, 32).
 9. The central locking system as claimed in claim 8,wherein amplitude modulation is used to apply the coded signals to thesupply voltages.
 10. The central locking system as claimed in claim 8,wherein pulse modulation is used to apply the coded signals to thesupply voltages.
 11. The central locking system as claimed in one ormore of the preceding claims, wherein the supply voltage lines (31, 310,32) and the signal and/or data lines (35) are laid in a concealedmanner.